The timing of Geithner's replacement depends on whether the White House can reach an agreement with the lame duck Congress on a deficit reduction plan to avoid triggering spending cuts and tax increases known as the fiscal cliff. If a deal can be reached before the Jan. 1 deadline, Geithner might leave as soon as it is completed.

If the solution is left for the next Congress, Obama may ask Geithner to stay, either to work on a deal or to reassure financial markets about the U.S. government's ability to trim the deficit.